SHORT NOTE The Herpetological Bulletin 132, 2015: 20-21
Discoglossus pictus tadpoles: egg cannibalism
FULVIO LICATA1*, SIMONE ANZÁ1 & EMANUELE MERCURIO2
1Via Umbria 6, 90144 Palermo, Italy. 2Via Faraona 6/a, 90039 Villabate (Palermo), Italy *Corresponding author email: [email protected]
The painted frog Discoglossus pictus is a monotypic species clutches (Escoriza, 2014). In general, cannibalistic oophagy distributed in North Africa, Malta and Sicily (Fromhage et al., has been observed in several other species of amphibians 2004; Zangari et al., 2006). It is widely distributed in Sicily, (Crump, 1983). This is the first time that cannibalistic oophagy where it occupies a broad range of habitats although it is has been observed in D. pictus tadpoles. linked mainly to temporary ponds, be they anthropogenic or Aquatic organisms living in temporary water bodies are not (Turrisi, Lo Cascio & Vaccaro, 2007). This species adopts subjected, during the hydroperiod, to intense natural selection intermediate or opportunistic trophic strategies during the and competition, which favour species with successful and adult stage, feeding mainly on insects and on other terrestrial efficient strategies. For example, species with synchronised invertebrates (Licata et al., 2012), while the tadpoles are explosive breeding can reduce the risk of cannibalism by generalist feeders. Since it is an euriecian species and can limiting the differences in size and development between occur in several aquatic habitats, painted frogs frequently individuals (Crossland & Shine, 2011). Since D. pictus does share their breeding sites with other species of amphibians. In not have a definite breeding season, spawning events occur Sicily it coexists with Pelophylax sp., Hyla intermedia, Bufo at different times, thus creating conditions for cannibalistic bufo, B. siculus and B. balearicus, as well as the invasive oophagy. The potential consequences of this behaviour involve Xenopus laevis (Lillo et al., 2011). population regulation and may impact on age class structure On 3 April 2009, during nocturnal surveys on a population (Crump, 1983). The benefits of practicing cannibalism are of D. pictus, we observed the predation of D. pictus eggs by gaining energy and nutrients, as well as reducing the number several tadpoles of the same species (Gosner stage 25; Fig.1a, of possible competitors. b). The observation was made in a breeding site located in a mountain pasture (UTM 33 S 0344451 4217051; alt. 800 m), on the western mountains of Palermo (northern Sicily; Fig.3). This is a temporary pond usually with a long hydroperiod (> 10 months), measures 60 m in length and up to 150 cm deep. It has plentiful aquatic vegetation and is surrounded by abundant riparian vegetation (Fig. 2). It has already been observed that D. pictus tadpoles may feed on other species’
a b Figure 1. Detail of temporary pond illustrating several D. pictus tadpoles eating eggs of its own species (a). Enlarged detail showing a tadpole of D. pictus eating eggs of the same species (b).
20 Herpetological Bulletin 132 (2015) Discoglossus pictus tadpoles: egg cannibalism
Figure 2 Photograph of the study area Figure 3 map of Sicily showing the study area (red star).
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